Method and apparatus for determining position in a pipe

ABSTRACT

A method and apparatus for determining position in a pipe provides for the precise determination of location and associated characteristics of each pipe joint of a well, cross country pipeline or other fluid transmission line. The system includes a passive or active radio identification device at each joint in the pipe or casing string. The devices are preferably sealed within the resilient seal positioned between each pipe or casing joint. A pipeline tool includes a radio transmitter and receiver, with the transmitter transmitting on a frequency selected for resonating the identification devices. The resonant response of each device is detected by a receiver in the pipeline tool, with the response transmitted to the surface via the wireline to which the tool is connected. Alternatively, the tool may include storage information means until the tool can be recovered from the well or pipe.

REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation of and claims the benefit of U.S.patent application Ser. No. 12/564,780, filed on Sep. 22, 2009 andentitled “Method and Apparatus for Determining Position in Pipe”, nowabandoned, which in turn is a continuation of and claims the benefit ofU.S. patent application Ser. No. 10/887,366, filed on Jul. 6, 2004 andentitled “Method and Apparatus for Determining Position in Pipe”, nowabandoned, which in turn is a continuation of and claims the benefit ofU.S. patent application Ser. No. 10/032,114, filed on Dec. 21, 2001 andentitled “Method and Apparatus for Determining Position in Pipe”, nowU.S. Pat. No. 6,759,968, which in turn is a continuation of and claimsthe benefit of U.S. patent application Ser. No. 09/286,650, filed Apr.6, 1999 and entitled “Method and Apparatus for Determining Position inPipe”, now U.S. Pat. No. 6,333,699, which in turn claims the benefit ofU.S. Provisional Patent Application Ser. No. 60/098,284, filed on Aug.28, 1998.

This application is related to the following patent applications: U.S.patent application Ser. No. 09/586,648, filed on Jun. 1, 2000, entitled“Method and System for Performing Operations and for ImprovingProduction in Wells”, and issued on Oct. 16, 2007 as U.S. Pat. No.7,283,061; U.S. patent application Ser. No. 12/173,693, filed on Jul.15, 2008 and entitled “Method and System for Performing Operations andfor Improving Production in Wells”, and issued on May 11, 2010 as U.S.Pat. No. 7,714,741; U.S. patent application Ser. No. 09/656,720, filedon Sep. 7, 2000, entitled “Method and System for Performing a CasingConveyed Perforating Process and Other Operations in Wells”, and issuedon Mar. 25, 2003 as U.S. Pat. No. 6,536,524; U.S. patent applicationSer. No. 09/843,998, filed on Apr. 27, 2001, entitled “Process andAssembly for Identifying and Tracking Assets”, and issued on Mar. 21,2006 as U.S. Pat. No. 7,014,100; U.S. patent application Ser. No.11/377,736, filed on Mar. 16, 2006, entitled “Process and Assembly forIdentifying and Tracking Assets”, and issued on Mar. 16, 2010 as U.S.Pat. No. 7,677,439; U.S. patent application Ser. No. 12/725,254, filedon Mar. 16, 2010, entitled “Process and Assembly for Identifying andTracking Assets”, and issued on Jan. 10, 2012 as U.S. Pat. No.8,091,775; U.S. patent application Ser. No. 10/323,536, filed on Dec.18, 2002, entitled “Method and System for Performing Operations and forImproving Production in Wells”, and issued on Jul. 15, 2008 as U.S. Pat.No. 7,400,263; U.S. patent application Ser. No. 10/726,027, filed onDec. 1, 2003, entitled “Method and System for Transmitting SignalsThrough a Metal Tubular”, and issued on Jun. 20, 2006 as U.S. Pat. No.7,063,148; U.S. patent application Ser. No. 09/536,953, filed on Mar.28, 2000, entitled “Apparatus and Method for Downhole Well Equipment andProcess Management Identification, and Actuation”, and issued on Dec.25, 2001 as U.S. Pat. No. 6,333,700; U.S. patent application Ser. No.12/044,087, filed on Mar. 7, 2008 and entitled “Systems, Assemblies andProcesses for Controlling Tools in a Well Bore”; U.S. patent applicationSer. No. 12/102,687, filed on Apr. 14, 2008, entitled “Systems,Assemblies and Processes for Controlling Tools in a Well Bore”; and,U.S. patent application Ser. No. 12/777,779, filed on May 11, 2010,entitled “Method and System for Performing Operations and for ImprovingProduction in Wells”, and issued on Oct. 25, 2011 as U.S. Pat. No.8,044,820.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates generally to devices for detectingintermediate points within wells, gas and oil pipelines, and the like,and more specifically to a system using radio frequency resonant devicesinstalled at various points in the well or pipe. A detector is insertedinto the pipe, and detects the resonant devices where installed totransmit location or depth and other information back to a station atthe surface or along the pipe. The present invention may provide for thestorage of the information gathered for downloading upon retrieval ofthe device from the well or pipe.

2. Description of the Related Art

The need for accurate measurement of the depth of a drilled well iscritical, as oftentimes the stratum of interest in the well, resideswithin a relatively narrow band. Wells are typically cased afterdrilling, with cement being poured between the casing and the wall ofthe drilled hole in order to seal and stabilize the hole. The casing andcement are perforated at the desired depth in order to access thestratum of interest (oil bearing deposits, gas, water, etc.), with thecasing and cement serving to prevent the flow and mixing of undesiredfluids with the fluid of interest from the well (e.g., water with oil,etc.).

In view of the above, it is critical that the well be perforated atprecisely the proper depth in order to avoid drawing an undesirablefluid into the well, and/or missing the desired stratum of interest inthe well. As wells typically extend from a few to several thousand feetbelow the surface in the case of oil and gas wells, the precisemeasurement of the depth of the well to within a few feet, poses adifficult problem. U.S. Pat. No. 5,279,366 provides an excellent anddetailed discussion of the problem in the Background of the Invention,columns 1 through 4, for further background.

Accordingly, numerous devices and systems have been developed in thepast for logging or measuring the precise depth of the well, forperforating the well or for other purposes as required. Such principlesas MRI (magnetic resonance imaging), gamma ray detection, and others,have been utilized in order to enable a detector lowered into the wellcasing to determine its position or depth within the hole. However, noneof the systems or principles utilized in the past, provide the neededaccuracy to enable an operator to determine precisely the depth of thetool within the hole. It is very easy for the well to be loggedincorrectly, or for the tool to detect the wrong joint or point in thecasing, and thus throw off all calculations and measurementsaccordingly. As the conventional well casing pipe has a length of somethirty feet, it will be seen that an error in the detection of one jointlocation, could cause a perforating gun or other tool to miss thestratum of interest completely.

Those skilled in the art are aware that the limitations of the prior artextend to other types of pipelines and the like, and are not limitedonly to generally vertical well bores. For example, the standardprocedure for examining a cross-country oil, gas, or other pipeline, isto “pig” the line, i.e., send a mechanical device (called a “pig”)through the line, generally by pneumatic means. The “pig” may sensevarious information relating to the condition of the line, or otherfactors, which information may be stored within the device until it isrecovered at some point in the line. However, any flaws or otherproblems in the line must be identified as to location, and themechanical “pigs” used for such operations have no means of determiningtheir position in the line. Rather, their location must be detectedexternally, by a worker stationed along the pipe or line as the “pig”travels through the line, and who logs the passage of the “pig” atvarious points along the line, relative to time. By knowing the timethat any information was gathered in the pipe, and the time of passageof the “pig” at various points, the location of any anomalies may beindirectly determined.

However, it will be seen that it can be difficult to determine theprecise location of various anomalies or other points of interest insuch a pipeline, as the detection of the passage of the “pig” throughthe line, is determined at only a relatively few widely separated pointsalong the line. Thus, when the record of the recovered “pig” isexamined, it may not be possible to narrow the location of some point ofinterest in the line, to an area smaller than perhaps a few hundred feetof pipeline, or perhaps more.

Accordingly, a need will be seen for a system which positivelyidentifies the location or depth of a well tool at various points withinthe well. The system comprises a plurality of passive or active radiofrequency resonant devices, which are installed at several, or all, ofthe joints in the well casing. Each of the devices is preferablyconstructed or tuned to provide a unique individual signal. A well toolis provided which transmits a low power and/or directional signal on anappropriate frequency for reception by the devices, which then resonateto provide a responding signal to the well tool. The responding signalpasses up the wire line to the well operator at the surface, who is ableto determine precisely the location or depth of the well tool in thewell. Alternatively, the information may be stored within the downholetool, for downloading into a computer or other suitable reading deviceat the surface, after recovery of the tool.

A further need will be seen for a system which is capable of positivelyidentifying the location of a tool which is passed through a pipeline orthe like, and recording the location corresponding to the tool atvarious points in time as the tool passes through the pipeline. Thesystem may utilize active or passive radio frequency resonant devices,with information being stored within the pipeline tool for laterrecovery when the tool is recovered from the line.

A discussion of the related art of which the present inventor is aware,and its differences and distinctions from the present invention, isprovided below.

U.S. Pat. No. 4,572,293 issued on Feb. 25, 1986 to James G. Wilson etal., titled “Method Of Placing Magnetic Markers On Collarless CasedWellbores,” describes the magnetic polarizing of well casing bypositioning one or more electromagnets within the casing, and activatingthe electromagnets to impart a permanent magnetic field at the locationof the electromagnet(s) within the casing or pipe. The magneticallypolarized area may be detected using a conventional magnetic readingcasing collar locator. The Wilson et al. method does not provide anymeans of differentiating between magnetically marked spots, nor ofprecisely positioning the magnetically polarized areas at predeterminedpoints in the casing. Moreover, Wilson et al. do not disclose any meansof logging or determining the position of a device in a cross country orother fluid pipeline, as provided by the present method and apparatus.

U.S. Pat. No. 4,630,044 issued on Dec. 16, 1986 to Rudolf Polzer, titled“Programmable Inductively Coupled Transponder,” describes a passiveradio identification device (PRID) including a memory for modulating theresponse signal when triggered by an appropriate transmitter. Polzerdescribes the placement of the resonating transponder on a movingobject, e.g., a railroad car, with the triggering transmitter having astationary mounting. This configuration is precisely the opposite of thepresent invention, with its stationary responding devices and triggeringtransmitter being mounted within a moving well hole or pipeline“pigging” tool. Moreover, Polzer makes no suggestion of using hisinvention for determining depth or other characteristics in a wellcasing or other fluid pipeline, as provided by the present invention.

U.S. Pat. No. 4,808,925 issued on Feb. 28, 1989 to Gary K. Baird, titled“Three Magnet Casing Collar Locator,” describes a magnetic device fordetecting pipe or casing joints in a well. The device provides aspecially shaped toroidal magnetic field, which magnetically affects theferrometallic casing and casing joints. A detector associated with thedevice detects variations in the magnetic field as the field changes asit passes each casing joint. Baird makes no provision for detecting anydifferences in the joints. Rather, each joint appears essentially thesame when detected, and the operator cannot determine precisely where inthe casing the device is located. Each joint must be counted in orderfor the location to be determined, and no other information is providedby the Baird device. Baird does not disclose any means of logging ordetermining the precise location of a pigging tool in a cross country orother than vertical fluid pipeline, as provided by the presentinvention.

U.S. Pat. No. 5,279,366 issued on Jan. 18, 1994 to Patrick L. Scholes,titled “Method For Wireline Operation Depth Control In Cased Wells,”describes the use of both magnetic and radioactive location markers in awell casing. The detector device is capable of detecting both highenergy radiation (gamma rays) and magnetic anomalies, thus making iteasier to confirm that well depth logs using either system separately,are properly “tied in.” The Scholes '366 U.S. patent provides anexcellent explanation of the problem of well depth control and logging,as well as the importance of a solution for the problem, in theBackground of the Invention portion of the disclosure, as noted furtherabove. However, Scholes does not provide any means of differentiatingbetween different joints or other locations along the length of thecasing, nor any radio frequency resonant means for doing so. Moreover,Scholes is silent regarding any form of logging or determining theposition of a tool in other than a vertical line, whereas the presentsystem may be applied to any fluid line in a generally vertical or otherthan vertical orientation.

U.S. Pat. No. 5,361,838 issued on Nov. 8, 1994 to Marion D. Kilgore,titled “Slick Line Casing And Tubing Joint Locator Apparatus AndAssociated Methods,” describes a device which is usable with a slickline, i.e., a monofilament metal or other line which does not carry anelectrical signal. The device relies upon an integral magnetic anomalydetector for detecting pipe or casing joints. When a joint is detected,the device drives a drag producing structure against the inner surfaceof the casing, with the drag registering as a momentary increase intension on the line at the surface as the device passes the joint. Thus,the Kilgore device can only be used when being drawn upwardly throughthe pipe, and does not utilize any radio frequency resonance means. TheKilgore device is also unworkable in other than a generally verticalline, whereas the present system is operable in any fluid line,regardless of its orientation.

U.S. Pat. No. 5,457,447 issued on Oct. 10, 1995 to Sanjar Ghaem et al.,titled “Portable Power Source And RF Tag Utilizing Same,” describes aradio frequency (RF) device providing an interrogation signal andreceiving a response from the interrogation signal. The device may bepowered by any one or more of several electrical sources, includingconventional battery power, solar or infrared cells, etc. However, Ghaemet al. are silent regarding a responding unit for their RF tag device.While the present invention makes use of an RF transmitter and receiverdisposed within a well downhole tool, pipeline pigging tool, or thelike, the present invention also makes use of inert or active resonantresponding devices which are triggered by the RF transponder device ofthe well or pipeline tool, which resonant responding devices are not apart of the Ghaem et al. disclosure.

U.S. Pat. No. 5,497,140 issued on Mar. 5, 1996 to John R. Tuttle, titled“Electrically Powered Postage Stamp Or Mailing Or Shipping LabelOperative With Radio Frequency (RF) Communication,” describes a smalland very thin radio receiver and transmitter, including a memory chipfor modulating the transmitted signal to provide certain specificinformation, e.g., routing, etc. The Tuttle disclosure provides for athin, flat battery for power of the device, and accordingly includes“sleep” and “wake” circuitry which is triggered by a transmission fromanother device. The present invention does not require any integralelectrical power in the specific form of an electric battery, butresonates when power is received from a nearby transmitter. The presentdevice may include active circuitry requiring electrical power, but theelectrical power is generated by electrochemical means using the fluidwithin the well or pipe, as an electrolyte. The Tuttle device is not aresonant device.

U.S. Pat. No. 5,626,192 issued on May 6, 1997 to Michael L. Connell etal., titled “Coiled Tubing Joint Locator And Methods,” describes a tubewhich is lowered into the well pipe string for locating pipe joints. Thedevice includes a fluid passage formed generally axially therethrough,and an electromagnetic joint detector which senses the increased mass ofeach joint, according to the disclosure. When a joint is detected, alateral valve is opened, which decreases the fluid flow resistancethrough the device and produces a pressure drop which is transmitted tothe surface. The Connell et al. device can only sense each joint, andcannot detect any difference between different joints, whereas thepresent device may provide means for differentiating between differentjoints in the well casing or fluid pipeline.

U.S. Pat. No. 5,720,345 issued on Feb. 24, 1998 to Timothy M. Price etal., titled “Casing Joint Detector,” describes a magnetic anomalydetector which detects the variations in magnetic flux across pipe orcasing joints, as in other devices of the prior art discussed furtherabove. The detector may also measure the distance traveled down theborehole, and correlate this distance with the number of joints passed.However, Price et al. make no provision for distinguishing betweendifferent casing or pipe joints, for determining precisely which jointis being passed at any given point. Also, as with other magnetic anomalydetectors, the device must be moving at some minimum velocity throughthe casing in order to generate the spike in electromagnetic energy forgenerating a detection signal. The present active or passive RF systemis operable at any practicable velocity in vertical, horizontal, orotherwise oriented fluid pipelines of virtually any type, i.e.,ferromagnetic or other material.

European Patent Publication No. 013,494 published on Jul. 23, 1980 toBritish Gas Corporation, titled “Measurement Of Velocity And/OrDistance,” describes a device which produces a magnetic anomaly in thewall of a ferrometallic pipe, and then detects the anomaly as the devicepasses. The device may thus measure its velocity through the pipe, bymeasuring the time between the production of the magnetic anomaly andits detection by another part of the device, with the distance betweenthe two components being known. As in other devices using magneticprinciples or means discussed further above, the British Gas devicecannot distinguish between different magnetic anomalies producedthereby, but can only count the total number of magnetic anomalies alongthe length of the pipe and provide a distance measurement based upon thedistance between the magnetic anomaly producer and detector. No RFmeans, nor use in other than a generally vertical downhole, is disclosedin the British Gas Corporation patent publication.

European Patent Publication No. 412,535 published on May 11, 1994 toMichael L. Smith, titled “Tubing Collar Position Sensing Apparatus, AndAssociated Methods, For Use With A Snubbing Unit,” describes a devicefor electromagnetically detecting tubing or joint collars forprogressively opening and closing the blowout pressure seals of ablowout valve. Accordingly, there is no need, and no teaching, of anymeans for distinguishing between different joints along the length ofthe tube or pipe. Smith notes that the measurement of the pipes cannotbe accomplished by odometer means alone, due to slight variations inpipe length and in the length of engaged threads at each coupling, towhich problem the present invention responds. Moreover, the presentsystem is adaptable to both generally vertical well holes, as well asgenerally horizontal or other orientation gas and other fluid lines.

European Patent Publication No. 651,132 published on May 3, 1995 to theHalliburton Company, titled “Method For Locating Tubular Joints In AWell,” describes a device which applies lateral pressure to the walls ofthe pipe whenever a joint is detected. The increased drag of the deviceincreases the tension on the line as the device is raised up the pipe,thus enabling the joints to be detected without requirement for anelectrical connection between the device in the pipe and the surface.The device described in the '132 European Patent Publication is the sameas that described in the '838 U.S. patent, and discussed further above.The same differences and distinctions noted in the above discussion, arealso seen to apply here.

Finally, European Patent Publication No. 730,083 published on Sep. 4,1996 to the Halliburton Company, titled “Method And Apparatus For Use InSetting Barrier Member In Well,” describes a device using conventionalmagnetic anomaly detection means for detecting pipe or casing joints,for positioning a barrier within the pipe or casing so that the barrieris not positioned on the joint. There is no need, and no teaching, forthe device to distinguish between different joints, as all that isnecessary for the Halliburton device is to determine that the barrier orseal will not be positioned directly on a joint.

None of the above inventions and patents, taken either singly or incombination, is seen to describe the instant invention as claimed.

SUMMARY OF THE INVENTION

The present invention comprises a method and apparatus for determiningposition in a pipe or the like, for detecting pipe or casing joints inan oil, gas, or other drilled well or pipe, and for distinguishingbetween joints. The system includes a passive radio identificationdevice (PRID), or alternatively an active device, installed at each pipeor casing joint, with a well or pipeline tool including a radiofrequency transmitter and receiver. The transmitter of the tool providesa constant transmission signal, which is attenuated or directionallymodified so as to be received only by an identification device at animmediately adjacent pipe or casing joint. When the device receives thetransmission from the tool, the identification device circuit resonatesto transmit a response, which is received by the tool receiver. Thesignal received by the receiver is then transmitted up the wirelinebetween the tool and the surface, where it is processed. Alternatively,the tool may include means for recording the information received, withthe information being downloaded from the tool upon retrieval of thetool at the surface or access point in a pipeline.

Information relating to each of the radio identification devices may bestored at the surface, with the operator being able to determine thelocation of the downhole tool at any time, and other characteristicswhich have been logged into the computer or information system, such aspipe or casing size, geological characteristics or stratum at anyparticular point as previously logged and entered into the system, depthof the well at that point, etc. Again, the present system is adaptablefor use in generally horizontal fluid (oil, gas, water, etc.) pipelinesas well as generally vertical downholes, and may be used in pipes ofvirtually any non-horizontal or non-vertical orientation as well. Thepresent invention may also utilize identification devices which providea distinct signal from one another, in order that the downhole tool isable to distinguish between each device, and therefore the joint withwhich any particular device is associated and the physicalcharacteristics previously logged at that location.

While passive radio identification devices (PRIDs) which resonate when aspecific frequency or frequencies are detected, may be used in thepresent invention, the present method and apparatus may also make use ofactive devices, i.e., devices requiring electrical power for operation.The present invention provides such electrical power in the form of anelectrical battery, with two dissimilar metals being provided in theresonant device, or the resonant device and tool, with the fluid withinthe well or pipe serving as an electrolyte for the device.

Accordingly, it is a principal object of the invention to provide animproved method and apparatus for determining position in a pipe or thelike, utilizing a radio frequency transmitter and receiver in a downholeor pipeline tool, with passive radio identification devices (PRIDs) oractive devices located at each joint in the pipe or casing.

It is another object of the invention to provide an improved pipelineposition determining method and apparatus which may include aninformation storage and retrieval system, such as a computer, at thesurface or outside the pipeline, with the downhole or pipeline tooltransmitting a signal to the system whenever a radio frequencyidentification device is detected.

Yet another object of the invention is to provide an improved pipelineposition determining method and apparatus which may use a tool havingrecording means therein, for recording information detected during toolpassage through the pipe, and for downloading the information from thetool recording means upon recovery of the tool.

It is a further object of the invention to provide an improved pipelineposition determining method and apparatus which computer or otherinformation system is programmed with various facts relating to each ofthe identification devices in the well or pipe, such as the stratum orgeological characteristics at each identification device installed inthe well, the pipe or casing diameter, distance between each of theidentification devices in the pipe or casing string, etc.

An additional object of the invention is to provide an improved pipelineposition determining method and apparatus which identification devicesmay be distinguished from one another, in order that the tooldistinguishes the specific identification device with which it iscommunicating at any given location in the well or pipe.

Still another object of the invention is to provide an improved pipelineposition determining method and apparatus which may utilize resilientseals disposed between each pipe or casing joint, for holding each ofthe identification devices in place.

Another object of the invention is to provide an improved pipelineposition determining method and apparatus which may utilize active RFidentification devices which draw electrical power from anelectrochemical source provided by dissimilar metals in the RF deviceand/or tool, with the fluid within the well or pipe serving as anelectrolyte.

It is an object of the invention to provide improved elements andarrangements thereof in an apparatus for the purposes described which isinexpensive, dependable and fully effective in accomplishing itsintended purposes.

These and other objects of the present invention will become apparentupon review of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a broken away perspective view in section, of a section ofwell casing and joint including the installation of a radioidentification device therein, and downhole tool including radiotransceiver means therein for communicating with the device.

FIG. 2 is a schematic elevation view of a drilled well and casing,showing the general operation of one embodiment of the present inventionand its communication with the surface and surface components associatedwith the invention.

FIG. 3 is a side perspective view in section of a pipeline couplingincorporating a radio frequency identification device in accordance withthe present invention.

FIG. 4 is a perspective view of a radio frequency identification deviceand loop antenna for use with the present invention.

FIG. 5 is a perspective view of a sleeve installable in a pipe,including the identification device and loop of FIG. 4.

FIG. 6 is an elevation view in broken away section of a pipeincorporating the present identification device and loop antenna, andincluding electrochemical energy generation means having dissimilarmetals disposed in the loop and in the detection tool.

FIG. 7 is an elevation view similar to that of FIG. 6, but having bothdissimilar metals incorporated in the antenna loop.

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention comprises a method and apparatus for determiningposition in a pipe or the like, for oil, gas, and other drilled wellshaving a jointed casing therein, and for cross country pipelines andother non-vertical gas, oil, water, and other fluid wells and pipelines.The present system provides for the determination of the preciselocation of a well or pipe tool within the casing or pipe, andassociated characteristics of the well or pipe at the location of thetool.

FIG. 1 provides a broken away perspective view in section of a wellcasing or pipe 10 formed of a plurality of sections 12, with eachsection 12 having a joint 14 therebetween comprising externally threadedconnecting ends 16 with an internally threaded mating coupling sleeve 18securing the two ends 16 together. Such joints 14 generally include atleast a slight gap 20 between each connecting end 16 of the casing orpipe sections 12, with a resilient O-ring 22 being placed in the gap 20at the time of assembly of the joint 14. A well downhole tool 24 is alsoshown in FIG. 1, at the lower end of a wireline 26 which serves both tosupport the tool 24 within the casing 10 and also for electrical powerand communication between the tool 24 and the surface, as shown in FIG.2 and discussed further below.

The well tool 24 includes a radio frequency transmitter and receiver 28therein, shown in broken lines in FIG. 1. A radio frequencyidentification device 30 is installed at each of the coupling joints 14of the pipe or casing string 10, as by sealing, imbedding, or otherwisesecuring the device 30 within the resilient O-ring seal 22 at each joint14. The radio frequency identification device 30 may be in the form of apassive radio identification device (known as a “PRID”). Such PRIDs areconventional and are used for merchandise security in the retailindustry, library security, etc., and generally comprise a solid stateprinted circuit which is configured to resonate upon receipt of radiofrequency energy from a radio transmission of appropriate frequency andstrength. Such devices do not require any additional power source, asthe energy received from the transmission provides sufficient power forthe device to respond with a weak and/or periodic reply transmission solong as it is receiving an appropriate transmission.

Alternatively, the responding device 30 may be in the form of an activedevice, requiring a separate source of electrical power (e.g.,electrical storage battery or other electrical power means). Suchdevices are also conventional, and may be configured to draw practicallyno electrical power until a radio frequency signal is received,whereupon they are electrically energized to produce a respondingtransmission.

The transceiver 28 enclosed within the well tool 24 is alsoconventional, and provides a radio frequency transmitted signal at theappropriate frequency to excite the PRID or active device 30 at anygiven joint 14 location. The transceiver 28 also includes a receivertuned to receive the response from the PRID or active device 30, whichresponse is provided on a different frequency than the transmissionfrequency used by the transceiver 28 in order that the transmittedsignal from the transceiver 28 does not interfere with the receivedsignal from the PRID or active device 30. The transmitter and antennasystem of the transceiver 28 are preferably configured to provide arelatively weak signal which can only be detected and responded to by aPRID or active device 30 in relatively close proximity to thetransceiver 28, i.e., within a foot or so distant.

Alternatively, the antenna of the transceiver 28 may be configured toprovide a highly directional signal, e.g., radially polarized orshielded to provide only a narrow radial transmission pattern, so thetransmitted signal from the transceiver 28 radiates essentiallyhorizontally from the transceiver 28 and well tool 24. In this manner,the transceiver 28 will not trigger more than a single PRID or activedevice 30 at any point in the passage of the transceiver 28 through thecasing pipe string 10, and will be in very close proximity, e.g., withina few inches, of the exact depth of the responding PRID or active device30. Alternatively, the receiving antenna may provide only a narrowradial reception band for accuracy.

FIG. 2 provides a schematic elevation view of a drilled well 32including a casing string 10 installed therein. The wireline 26 is shownextended from the conventional wireline head 34 (comprising a reeland/or other extension and retraction means for the wireline 26, andconventional means for communicating electrical power and signals to andfrom the wireline 26 and thus to the well tool 24 at the lower endthereof), with the well tool 24 disposed at a specific joint 14 a havinga specific PRID or active device 30 a installed therein. The radiofrequency transmission of the transceiver 28 triggers a response fromthe adjacent PRID or active device 30 a, causing the device 30 a toresonate according to the transmitted frequency from the transceiver 28and to transmit a responding signal on a different frequency. Thedifferent frequency of the responding device 30 a transmission isdetected by the receiver portion of the transceiver 28 in the well tool24, and is relayed back to the wireline head 34 for processing at thesurface.

In many instances, the line 26 used to lower the tool 24 into the hole,and to withdraw the tool 24 from the hole, is a non-electric line.Accordingly, tools 24 used with such non-electric lines includerecording means therein, with the data recorded by the recording meansbeing downloaded to the remotely located computer and database afterrecovery of the tool from the hole or pipeline. Such data recording welltools are conventional, and are in use in the well and pipelineindustry.

Normally, a drilled well is “logged” before casing is installed, inorder to determine the exact depths of specific geological structures(e.g., impervious rock, oil and/or gas bearing strata, etc.). Theinformation logged, as well as other information, such as the diameteror size of the casing, well name and/or number, depth of the well, etc.,is entered into an information storage and retrieval system database,conventionally a computer 36 including appropriate programming for theapplication.

Thus, as the well downhole tool 24 passes each PRID or active device 30,30 a at each joint 14, 14 a along the depth of the assembled well casing10, each device 30, 30 a responds with a signal which is relayed to thesurface and ultimately to the computer 36. By “counting” the number ofPRIDs or active devices 30, 30 a which the well tool 24 has passed as itis lowered through the casing 10, and comparing each consecutive PRID30, 30 a with the corresponding data previously logged, the computer 36can indicate the conditions at the location of the well downhole tool 24in the well casing 10. As an example, previously logged data mayindicate that an oil bearing stratum is located between 12,000 and12,200 feet below the surface. As the length of each of the casingsections 12 is known, the computer 36 need only divide the depth of thestratum by the length of the casing sections 12 to determine how manycasing sections 12 (and thus how many joints 14, with their associatedPRIDs or active devices 30) lie between the surface and the desiredstratum. This allows the well casing 10 to be perforated accurately atthe desired strata, assuring that good flow of the desired substance isobtained without any mixture of undesired substances (water, etc.).

It will be seen that each of the PRIDs or active devices 30, 30 a may beconfigured to provide a distinct and unique response, if desired, or atleast several different responses may be provided for the plurality ofPRIDs or active devices 30 used in the present invention. Such devicesmay be configured to provide different frequency responses, and/ormodulation of the responses in some manner (amplitude, frequency, pulse)in order for each device to provide a distinct response.

In this manner, each PRID or active device 30, 30 a, etc. may beinstalled along the casing or pipe string 10 with each providing adifferent response. The different responses corresponding to each of thePRIDs are entered into the computer 36. Thus, information is availableas to the exact location of each independent PRID or active device 30,30 a, etc. This may be important in the event that the system misses aresponse by one or more of the devices 30 installed along the pipecasing 10. In such a situation, if all of the devices 30, 30 a, etc.provided identical response signals, the missing of e.g., two of thePRID or active device response signals would result in an error of aboutsixty feet in the determination of the depth of the well tool 24. Byproviding each PRID with a distinct response signal, the computer 36 isable to determine the precise location of any given PRID or activedevice, even if a response signal was not received from one or more ofthe devices along the casing string 10.

It will further be seen that it is not absolutely essential to provide aseparate and distinct response signal for each of the PRIDs or activedevices 30 along the string 10. Provision for e.g., five differentresponses, with each identical response being installed five casingsections apart from one another in a repeating pattern, i.e., 1, 2, 3,4, 5, 1, 2, 3, 4, 5, etc., would provide sufficient resolution for thelocation of the well tool 24 within the pipe or casing string 10, evenin the event that responses from one or two, or even four consecutive,PRIDs or active devices 30 were not received. Thus, an accuraterepresentation of the location of the well tool 24 at each joint 14 maybe provided by the present invention.

While the discussion to this point has been directed to the well ofFIGS. 1 and 2, it will be seen that the present invention is not limitedonly to use in generally vertical drilled wells and the like. Thepresent method for determining position in a pipeline may be used inother pipeline environments, such as generally horizontal cross countrygas, oil, or other fluid pipelines as desired, or in any pipelineorientation.

As an example of such use in a cross country pipeline, such lines areconventionally used for the transport of oil, gas, etc. between variouspoints. It is necessary to inspect the interior of such lines from timeto time, and this is conventionally accomplished by means of anautomated tool, called a “pig,” which is passed through the pipeline(generally “blown” through the line by increasing the pressure on oneside of the pipeline relative to the tool). Such tools may include meansof detecting various flaws within the pipeline, but may not include anymeans of determining their position in the line. Accordingly, a workerstationed along the pipeline logs the time when the “pig” passes, andtravels to another point along the line where the process is repeated.When the “pig” is recovered from the pipeline, the data recorded by theconventional data recording means therein, is downloaded to some form ofdata recovery means (e.g., computer and database). The times at whichany anomalies in the line were recorded by the data recording means inthe “pig” are noted and compared to the times logged by the worker whonoted the passage of the “pig” at various points along the line.

As can be seen, this provides only a very approximate idea of theposition of the “pig” at any point where a pipeline anomaly wasrecorded, by interpolation of the times of passage at various points.Thus, the narrowing of the location where a more detailed inspectionand/or repair is required, can be time consuming and costly. Moreover,such a system may result in the unnecessary replacement of a largerlength of pipeline than is absolutely required, merely because theprecise location of a flaw could not be accurately determined.

The present system provides a solution to the above problem, by means ofinstalling a series of PRIDs or active radio frequency devices atvarious predetermined locations within the pipeline. Such PRIDs oractive devices may be installed at joints in the pipeline, somewhat inthe manner described above for the well casing or pipe, or in otherareas of the pipeline as desired. The “pig” may include a transmitterand receiver similar to the conventional units which may be used in welldownhole tools as described above, with the transmitter unit sending acontinuous signal which is received by each of the radio frequencydevices in turn as the “pig” travels through the pipeline. The devicessequentially provide responses as they are triggered by the transmitterin the “pig,” with the receiver in the “pig” receiving the respondingsignals and the conventional recording means within the “pig” storingthe location signals from the PRIDs or active devices, in a mannersimilar to that described above for well downhole tools having selfcontained recording means therein.

The data stored within the recording means, including the respondingsignals from the PRIDs or other active responding devices, is downloadedafter the “pig” is recovered and is examined to determine if any flawsor other anomalies are present in the pipeline. If an anomaly is notedin the pipeline data, its location is easily determined relativelyprecisely by noting the PRID or active device signal at that location,or to either side of the location of the anomaly. Workers may thenrepair the problem as required, without need to spend substantialamounts of time and effort searching a relatively long length ofpipeline for the problem, and/or replacing a large amount of the line inorder to be sure that the problem was taken care of.

It may be desirable to provide a separate, relatively short section ofpipe which incorporates a responding device therein, and which may beadded to an existing pipeline or string as desired. Such a unit 38, or“sub,” is shown in section in FIG. 3 of the drawings. The “sub” unit 38includes an internally threaded portion 40 at one end thereof and anexternally threaded portion 42 at the end opposite the internallythreaded portion 40, thus allowing the sub unit 38 to be assembledbetween two sections of pipe or string to act as a joint therebetween.The sub unit 38 is particularly configured for the installation of aPRID or active device therein, by means of the internal groove orchannel 44 provided circumferentially about the interior of the unit 38.The channel 44 may include a PRID or other active radio frequencyresponse device 30 imbedded therein, by means of a radio frequencytransparent material 46 (e.g., resilient rubber or elastic material,plastic, etc.) installed within the groove or channel 44 for securingthe PRID or active device 30 therein. In this manner, a series of such“sub” joints 38, with each including a PRID or active device 30, may bemanufactured and installed in the field in a pipeline or well string, asdesired. It will be noted that while threaded connecting ends 40 and 42are illustrated for the sub joint 38 of FIG. 3, that other connectingmeans (flanges, etc.) may be provided as desired and in accordance withthe configuration of the line in which the sub joint is to be installed,without departing from the scope of the present invention.

As noted further above, the signal strength of the responding devices(PRIDs or active devices) need not be particularly high, as the receiverin the pipeline tool will always be located quite close to the passiveor active responding device. However, additional signal strength may bedesirable in certain circumstances, particularly in the case of PRIDswhich do not have any supplemental electrical power but rely upon theelectromagnetic energy provided by the transmitted signal. Accordingly,it may be desirable to provide some means of enhancing the signalreceived for such PRIDs. One such means is disclosed in FIG. 4, wherethe PRID or active device 30 includes a circular loop antenna 48installed therewith. The loop antenna 48 is configured to fit closelywithin a corresponding section or joint of the pipeline, casing, etc.,as indicated by the section of loop antenna 48 shown installed in thesection of sub joint 38 of FIG. 3.

The loop antenna 48 also includes a wrap or encircling portion 50surrounding the corresponding PRID or active device 30 installedtherewith. The relatively large antenna loop 48 (compared to therelatively small antenna of the PRID or other device 30, itself) iscapable of receiving considerably greater signal strength from thetransmitter as it passes that point in the pipe, as it completelysurrounds the transmitter during the transmitter passage. The wrap ofencircling antenna loop component 50 surrounding the PRID or activedevice 30, thus re-radiates the received signal to the device 30, thusproviding a much stronger signal to the device 30 than would be the casewithout the supplementary loop antenna 48.

In some instances, it may not be possible or convenient to install aPRID or other radio frequency responding device 30 at a joint locationin a pipeline or pipe string. Accordingly, FIG. 5 illustrates a means ofinstalling such a responding device 30 at some intermediate point in apipeline or string, without need for specialized pipe components. FIG. 5illustrates a sleeve 52 formed of radio frequency transparent material(plastic, etc.) which may be installed within a pipeline or string. Thesleeve 52 includes a PRID or active responding device 30 therein, andmay also include an antenna loop 48 therein as well. As in the case ofthe responding device 30 and antenna loop 48 of FIG. 4, the antenna 48may include a smaller loop 50 encircling the PRID or active device 30,and providing the benefits noted further above. The responding device 30and antenna loop 48 may be encapsulated into the wall of the plasticsleeve 52 during manufacture.

As noted herein, the responding devices 30 may be of two classes. Oneclass comprises PRIDs, or passive radio identification devices, which donot require any additional form of electrical power. However, the otherclass of active responding devices requires some form of electricalpower to provide a responding radio frequency transmission. Accordingly,such devices also require some form of electrical power source.Conventional electrical storage batteries may be provided for suchactive devices, if so desired, with long battery life being achieved bymeans of “sleep” circuits in such active devices to reduce electricalpower requirements to practically nil when no radio signal is beingreceived.

However, the present invention may also include another means ofgenerating electrical power for such active responding devices, asillustrated in FIGS. 6 and 7. FIGS. 6 and 7 show an O-ring, respectively22 a and 22 b, installed within respective gaps 20 a and 20 b betweenpipe sections 12 a, 12 a and 12 b, 12 b and surrounded by a pipecoupling, respectively 14 a and 14 b in the two drawing Figures. FIG. 6also illustrates a portion of a pipe or well tool 24 a disposed withinthe pipe 12 a. The groove or gap 20 a of FIG. 6 includes a firstelectrochemically reactive metal component 54 therein, with the well orpipeline tool 24 a including a second electrochemically reactive metalcomponent 56 disposed to the outer surface thereof. The two metalcomponents 54 and 56 are formed of dissimilar metals, e.g., copper andzinc, etc., having different electrolytic capacities.

The fluid 58 which flows through the pipeline or well bore casing 12 a,normally provides some electrical conductivity and serves as anelectrolyte for the dissimilar metals 54 and 56. (The fluid 58 is notshown in the gap 20 a in FIG. 6, for clarity in the drawing Figure.)Accordingly, an electrical potential is developed between the twodissimilar metals 54 and 56, which may be used to provide the relativelysmall amount of electrical power required for the operation of an activeradio identification device (not shown in FIGS. 6 and 7, but shownschematically in other drawing Figures). It is noted that while noelectrical connections are shown in FIGS. 6 and 7, such connections areconventional and well known in the art.

As an example, a first electrical connector may be connected between oneterminal of the active responding device and the first dissimilar metalcomponent 54, with a mutual ground connector between the second terminalof the responding device and the second metal component 56 of thepipeline tool 24 a, as by means of an electrical contact between theouter surface of the tool 24 a and second terminal of the respondingdevice. The electrolytic reaction of the dissimilar metals 54 and 56 andat least slightly electrolytically reactive fluid 58, results in acurrent flow between the two metals 54 and 56 and across the respondingdevice, by means of the electrical contact between the tool 24 a andsecond terminal of the responding device.

FIG. 7 illustrates a variation upon the assembly of FIG. 6, with the twodissimilar metal components 54 a and 56 a both being installed withinthe wall of the pipe 12 b, in the gap 20 b formed therein at theassembly joint. The fluid 58 flowing through the pipeline (not shown inFIG. 7, for clarity in the drawing Figure) flows around and past the twometal components 54 a and 56 a, thus serving as an electrolyte betweenthe two. The two components 54 a and 56 a may be electrically connectedto the terminals of an active radio identification device, as isconventionally done in the case of electrical storage battery power forsuch devices. However, the provision of the two electrochemicallydissimilar metals 54 a and 56 a (or 54 and 56, in FIG. 6) serves togenerate a certain amount of electrical energy, which is sufficient tosupply the relatively small electrical energy needs of such active radioidentification devices as used in the present invention.

In summary, the present method and apparatus for determining position ina pipeline provides a much needed system for easily and preciselydetermining the position of a well tool within a drilled oil, gas, orother well having a jointed well casing, or the position of a pipelinetool or “pig” within a pipeline. The present system is relatively simpleand yet robust, with the PRID or active devices being used having greatdurability and reliability. The imbedding or sealing of each of thePRIDs or active devices within the resilient O-ring (rubber, Teflon; tm,etc.) located at each casing or pipe joint, provides further protectionfor the devices while simultaneously locating them precisely at eachjoint. The prior logging of the well hole characteristics, such asgeological characteristics, depth of various strata of interest, wellname and/or number, diameter of the casing to be used, etc., into adatabase, provides an operator at the surface with all informationnecessary to determine the appropriate action to take and theappropriate positioning of the tool for perforating the casing or otheroperations in the pipe.

It will be appreciated to those skilled in the art that the inventioncan be used in any type of pipe or casing, either vertically orhorizontally oriented, and as found in refineries, chemical plants, oiland gas pipelines, underground water systems, or in any system where itis necessary to know the exact location of a tool or instrument beingrun through a pipe in any particular pipe system. The use ofconventional self contained recording means within the well or pipelinetool, enables the present invention to be used with “slickline” typetools as well, as no electrical or other communication is requiredthrough the line. Accordingly, the present system will provide welldrillers and operators, pipeline operators, and others working withsimilar systems, with a much needed means of quickly, easily, andrelatively inexpensively, determining the precise location of a welltool in a well and correlating that location with previously loggedinformation for accurate operations.

It is to be understood that the present invention is not limited to thesole embodiment described above, but encompasses any and all embodimentswithin the scope of the following claims.

I claim:
 1. A fluid pipeline comprising: a pipe having a plurality ofsections with adjoining sections defining a joint including a gaptherebetween; and at least one radio frequency identification deviceinstalled within said pipe and configured to receive a radio frequencysignal from a transmitter in the pipe and to provide a distinct responsesignal, wherein each of said at least one radio frequency identificationdevice is installed within the gap of a different one of the jointsdefined between adjoining sections of the pipe.
 2. The fluid pipeline ofclaim 1 wherein said pipe has a substantially horizontal orientation. 3.The fluid pipeline of claim 1 further comprising: a seal positioned insaid joint.
 4. The fluid pipeline of claim 1 wherein said at least oneradio frequency identification device is sealed.
 5. The fluid pipelineof claim 1 wherein said at least one radio frequency identificationdevice is an active radio frequency identification device.
 6. The fluidpipeline of claim 1 wherein said at least one radio frequencyidentification device is a passive radio frequency identificationdevice.
 7. The fluid pipeline of claim 1 wherein a plurality of radiofrequency identification devices are installed within said pipe.
 8. Thefluid pipeline of claim 7 wherein said pipe has a plurality of jointsand wherein each of said plurality of radio frequency identificationdevices is installed within the gap of a different joint of saidplurality of joints.
 9. The fluid pipeline of claim 7 wherein each ofsaid plurality of radio frequency identification devices is sealed. 10.The fluid pipeline of claim 7 wherein the distinct response signal ofone of said plurality of radio frequency identification devices isidentical to the distinct response signal of another of said pluralityof radio frequency identification devices.
 11. The fluid pipeline ofclaim 7 wherein each of said plurality of radio frequency identificationdevices is an active radio frequency identification device.
 12. Thefluid pipeline of claim 7 wherein each of said plurality of radiofrequency identification devices is a passive radio frequencyidentification device.
 13. The fluid pipeline of claim 1 wherein atleast one of said at least one radio frequency identification devices issealed by means of a resilient O-ring seal positioned in the gap. 14.The fluid pipeline of claim 1 wherein the pipe is well casing.
 15. Thefluid pipeline of claim 14 wherein the well casing has a substantiallyhorizontal orientation.
 16. The fluid pipeline of claim 14 wherein eachof the adjoining sections of the well casing are secured together by aseparate coupling sleeve.
 17. The fluid pipeline of claim 13 wherein thepipe is well casing.
 18. The fluid pipeline of claim 17 wherein the wellcasing has a substantially horizontal orientation.
 19. The fluidpipeline of claim 17 wherein each of the adjoining sections of the wellcasing are secured together by a separate coupling sleeve.